RB30 Facts, Figures and Helpful Hints

RB30-TB42 Nikki carby tuning procedure(temporary)

Below tuning procedure is from repair manual.

Carburetor lean/rich diagnostics

Above tuning procedure only tunes the AFR at idle rpms(hence the reason it's called "idle mixture screw")

Above idle rpms, jets, airbleeds & accelerator pump, etc takes more control of the AFR.
Therefore, if the symptoms of "bad tuning"(see below for the list) continues, then the carby may need a rebuild.
Before rebuilding a carby, it's IMPORTANT to rule out any electrical issues that may be causing issues with the carby.
These include petrol pump issues, weak or broken connections with the wires/connectors to petrol pump or the solenoids that control the valves inside the carby.

Symptoms of Lean and Rich

Here are some basic symptoms, some duplicate

Lean

Reduced Power - Sluggish at certain RPM's. Wide open throttle yields no power. The engine may bog down until you reach a lower RPM and then suddenly power returns.
2)Difficulty Starting
3)Spark plugs are clean - No residue. Insulator may be white.
4)Runs better at higher altitudes - AFR becomes normalized due to reduced atmospheric pressure allowing fuel into the venturi easier.
5)Backfires - Popping on deceleration for a lean idle circuit or backfires in general.
6)Runs on choke - The vehicle may run on choke when it's warm but stalls if the choke is turned off.
7)Idles poorly - Fluctuations in idle RPM, stalling
8)Engine runs hot - Due to more oxygen than fuel combustion temperatures are hotter reflecting on a temp gauge.
9)Hanging idle - The engine idles high and then drops and stalls. Typically a lean condition caused by an air leak between the butterfly and the head or a vacuum line that is not attached.
10)Sharp Odor - The exhaust smell may be sharp and burn your nose. This is NOx or Nitrogen Oxide. It's created by high temperatures in the combustion process between nitrogen and oxygen. Although NOx is present in all exhaust it can be more pronounced in higher combustion temperatures associated with lean conditions with more oxygen. More oxygen=higher burn temp

Rich

1)Reduced Power - It has less power but seems to be OK and runs.
2)Reduced Fuel Mileage - Your using more fuel per cycle so your mileage becomes worse.
3)Rough Idle - Combustion takes a just a bit longer with more fuel and at lower RPM's the engine can idle rough. Unlike a miss-fire on a spark plug this idle seems fine if the idle is turned up just a bit.
4)Spark Plugs Black - Carbon buildup on insulator and electrodes of plug. Wipes off your finger as sooty and back. Carbon is a conductor of electricity and getting considerable carbon buildup from a rich condition with ground the inner electrode down the positive insulator. When this condition occurs there will be no spark. You can clean the sparkplug with carburetor cleaner and re-use.
5)Exhaust Exit is Black and Sooty - Excessive carbon buildup in the exhaust is thick and overly grimy. A properly jetted carburetor will leave a nice grey scale color in the end of the exhaust pipe.
6)Odor of unburned fuel - In cases of a very, very rich mixture you may smell some unburned fuel coming out of your exhaust. This could be due to a grounded out sparkplug from too much carbon buildup preventing the combustion process in a cylinder or so much fuel that combustion is not occurring.
7)Runs better with more air - If you remove your air filter and the engine begins to run a bit better with more oxygen in the mix it is likely you have a rich condition.
8)Runs worse at altitude - If the bike starts to run worse at higher altitude with reduced oxygen, it's likely a rich condition.
9)Black Smoke - If you have black exhaust when you rev it, it's rich. You can get a light colored rag and place it over the exhaust lightly and rev it to see if you get carbon/black residue on the rag.

Sources(meant for motorbikes, but the principles are the same) :
symptoms-of-lean-or-rich-carb-settings
lean-vs-rich/

RB30 Patrol Fuel Plumbing Diagram

This is a diagram and the related actual pictures of the RB30 Patrol fuel plumbing system.

Photo bomb No 2

Photos of tank end. This is not the factory tank, but a LRA(Long Range Automotive) made custom "long range" tank(only holds 68 litres). However, the connections/plumbing to the tank are the same afaik. The in tank pump/sender is the factory one from the original main tank.

Petrol pump modification/redundancy pump/Aftermarket External Replacement pump(RB30)

This is how I added an external redundant fuel pump for my RB30 Patrol.(For carby model, not EFI)
I did this after encountering possible few issues with the in tank stock pump.
Replacement pump for the in tank stock pump was around $130, and I thought it's bit too dear.
This external pump is around $20(including postage). Fuel pumping pressure is around 3-4psi, so it's low pressure pumping
that is required for the RB30 Patrol(factory carby model).

This is the pump I used.
http://www.ebay.com.au/itm/New-Elect...b=1&rmvSB=true

I tested the pump and it works pretty well. I fitted it onto the chassis above the tank, very close to original pump plumbing. I attached the supply line from this external pump to long enough fuel hose and wire tied it to the chassis to attach to the petrol supply line, in case in tank pump fails in future.(in tank pump turned out to be ok). +12V and earth connections were tapped from the original connections to the in tank pump & I put an accessible switch to turn on the external pump, when or if it needed in the future.

The pickup plumbing line for the external pump was created out of redundant line on the stock pump assembly.(pictures attached). I also added a fuel strainer for the tank & attached both pump pickup hoses to the same strainer.


P.S.
Even though, I installed the above external pump as a redundancy, it's also a good and cheaper external replacement pump in place of the factory in tank pump. It may even be possible to install the above external pump without having to totally drop the tank.
(Removing rear fittings of the tank and removing the rear driveshaft can help with that).

The only issue is that the internal pickup hose need to be installed in order to be able to pump the petrol from the tank. So, in tank pump/sender assembly removal is still necessary.

Below is the link to the above thread.

RB30 Patrol FPCU(Fuel Pump Control Unit) modified replacement

I have very carefully cut a small angled slot in the bottom of the cooling system bleed screw.

I only cut the slot to about half way through the screw so the air would rise up and out.

I made real sure the edges of the cut were filed so as not to interfere with the thread.

The bleed screw is shown by the yellow arrow.

I hope this will make bleeding of the cooling system easier, because I nearly dropped the screw after I undid it too far.

The slot should allow the threads to grip, while letting air escape.

I forgot to cut the slot while I had the system draining.

After filling and burping the system I waited until the next day so the system was cool.

I only lost a few drops of coolant with the screw out.

Hey blokes,

I'm trying to sort out a couple of small items, main one right now is that she is running rich, and using a fair bit more fuel than usual (although it seems ok when driving), it mainly seems very rich at idle.

I don't have an afr gauge, but I have adjusted the idle to where it seems happiest, best idle speed and driving performance etc. and doesn't seem to blow any fuel smoke when revving.

Air filter is not too dirty, timing is at about 15 degrees from what I can see, Carbie was rebuilt professionally last year. In addition I have checked the auto choke operation as per photos below.

Attachment 71630Attachment 71631Attachment 71632

Photos show the alignment of the choke, the butterfly when cold and after reaching normal temp. I can take it to the fella who rebuilt the carb for me but I do like fixing stuff myself.

Any ideas what to look for / at to track the problem down?

Dom's Post #99 and this link should help you.

http://www.nissanpatrol.com.au/forum...ics#post680567

Page 4A-7 in the Haynes manual deals with the auto choke.